Policy-based routing (PBR) is a mechanism that makes routing decisions based on user-defined policies. PBR includes local PBR, interface PBR, and smart policy routing (SPR).
Traditionally, devices search routing tables for routes of packets based on their destination addresses and then forward the packets. Currently, more users require that devices route packets based on user-defined policies. PBR allows network administrators to make user-defined policies to change packet routes based on source addresses, packet size, and link quality in addition to destination addresses.
Benefits
PBR has the following advantages:
Allows network administrators to make user-defined policies for routing packets, which improves flexibility of route selection.
Allows different data flows to be forwarded on different links, which increases link usage.
Uses cost-effective links to transmit service data without affecting service quality, which reduces the cost of enterprise data services.
Local PBR
Local PBR applies only to locally generated packets, such as ping packets.
Local PBR on a device can have multiple local PBR nodes. Each local PBR node has a priority. The device attempts to match locally generated packets with rules bound with local PBR nodes in descending order of priority.
Interface PBR
Interface PBR applies only to packets received from other devices, but not to locally generated packets such as local ping packets.
Smart Policy Routing
Smart policy routing (SPR) allows devices to select routes based on link quality and requirements for link quality.
